The invention relates to a tubular product comprising at least three layers, a base layer, an innermost layer made of plastic by continuous extrusion, the base layer and the innermost layer having poor adhesion to each other, and a tie layer between the base layer and the innermost layer.
The invention further relates to an extrusion apparatus comprising means for extruding a multilayer parison comprising at least an inner plastic layer and a tie layer.
The invention also relates to an extrusion method wherein a multilayer parison comprising at least an inner plastic layer and a tie layer is extruded.
In this type of extrusion apparatus, pressures are high and mechanical stresses are great in the nozzle section, i.e. in the area of the central extrusion conduit. The present structures also needlessly prevent some of the possibilities of use of the apparatus.